Updated MongoDB driver and extensible JSON library

[Tal Liron]

I finally found time to update these to work with the latest Nashorn 
builds from Mercurial. Fixes involves a few issues with unwrapping 
ScriptObjectMirror and a smaller API changes (NativeArray).

MongoDB JVM 2.1.4
https://code.google.com/p/mongodb-jvm/

This manages conversion to and from native Nashorn types and BSON, with 
support for MongoDB's various type extensions ("$date", "$oid", etc.). 
It uses the MongoDB Java driver for BSON encoding/decoding. Also 
included is a complete JavaScript driver for MongoDB, optimized for 
Scripturian environments.

JSON JVM 1.1.2
https://code.google.com/p/json-jvm/

This is a fast JSON converter using native Nashorn types, and its 
extensible (so it can support the MongoDB extended types, for example).